MARINETTE, Wis. — A 15-year-old student who held about two dozen students and a teacher hostage for several hours in a classroom at a Wisconsin high school died Tuesday at a hospital from a self-inflicted gunshot wound, authorities said.

Sophomore Samuel Hengel shot himself after police stormed a classroom at Marinette High School on Monday night, said police chief Jeff Skorik. Hengel, of Porterfield, had been holding most of the students and their social studies teacher hostage for several hours. No one else was wounded.

The teenager allowed one of his hostages free a short time after he took over the classroom after the girl's mother tried to call her daughter and couldn't reach her, said Principal Corry Lambie. Five more of his hostages were let out after about six and a half hours, and finally the other students and their teacher Valerie Burd emerged unharmed.

The terrified high schoolers trapped in the classroom worked desperately to keep their captor calm by chatting and laughing with him about hunting and fishing. Student hostage Zach Campbell said the gunman seemed depressed, but he didn't think he meant his classmates any harm.

"I didn't know really what to think. I was just hoping to get out alive," Campbell said Tuesday on CBS' "Early Show." "He didn't want to shoot any of us."

Campbell told The Associated Press that six of the gunman's close friends were in that class.

Authorities also said they did not know what might have motivated the boy who made no demands or requests during the standoff.

"As far as what caused this, it seems to be a mystery," Skorik said. "We have not been able to identify anything that precipitated this incident."

Skorik said the suspect fired three shots immediately before police entered the room, but he had also fired at least two or three shots before that. He shot into a wall, a desk and equipment in the room, but he was not aiming at any students, Skorik said. The shooter was carrying a 9 mm semi-automatic and a .22 caliber semi-automatic, and he had additional ammunition in his pocket and a duffel bag with more bullets was found at the scene, the chief said. A knife was also found in the room, he said.

A bomb-sniffing dog was brought in to check the building for explosives and none were found, the chief said. He said it was not clear where the boy got the weapons or how he sneaked them into school.

The shooter entered the classroom, where he was a student, at around 1:30 p.m., Skorik said.

Marinette Schools Superintendent Tim Baneck said the student started class without any weapons. He then asked to use the restroom, and when he returned he was carrying the duffel bag containing the two guns and ammunition, Baneck said.

It wasn't until more than two hours later that the principal learned that neither the teacher nor any of the students from the class had been seen, Skorik said. He went to investigate and was threatened by the shooter to "get out of here," Skorik said. Lambie said the classroom was dark and locked so he used a key to enter and that's when the teen pointed a gun at him and told him to leave. The principal said he left and was able to take one of the students with him.

Campbell said the class was watching a movie when the gunman shot the projector, then fired a second round. He had two handguns and refused to let anyone leave, Campbell said. He demanded everyone dump their cell phones in the center of the room. When the gunman's own cell phone rang, the boy snapped it in half, Campbell said.

He wasn't interested in talking with the teacher and told her to be quiet, Campbell said. But the gunman chatted with his fellow students, who tried to keep him talking about how he hunted and about fishing. Students even got the gunman to laugh, Campbell said.

The gunman refused to communicate with officials during the standoff, Skorik said, but allowed the teacher, Burd, to speak with them by phone.

"The teacher was nothing short of heroic," Skorik said. "I think she kept a very cool head. She was able to keep the suspect as calm as possible. I heard that she took the responsibility of trying to assure the other students they were going to be OK. We really give that teacher a lot of credit for being able to keep a cool head under a stressful situation."

Firefighters kept people away from the school. Anxious parents met throughout the evening with officials at the county courthouse. After several hours, the boy let Campbell and four other students out to use the bathroom. Police outside the classroom whisked them to safety.

About 20 minutes later, Skorik said, officers heard three shots and broke down the door. The gunman, who was standing at the front of the classroom, shot himself as officers approached, the chief said.

Students were taken by bus to the courthouse, where they were reunited with their parents.

Keith Schroeder, a former Marinette middle school teacher, said he had the gunman as a student and also knows the boy's teacher well. He said the teen's family is extremely involved in all their boys' lives.

"He's a fine young man, and I'm totally taken aback," Schroeder told The Associated Press. "Surprised, flabbergasted to say the least because this is a great family. It doesn't fit any of the things or the molds that you read about people. I couldn't say enough good things about the family."

Marinette, a city of about 12,000 people, lies about 50 miles north of Green Bay on the border with Michigan's Upper Peninsula. About 800 students attend the high school, according to its website.

City Councilman Bradley Behrendt said the district spent "a whole bundle of money" on classroom doors to make them more secure, but the school doesn't have metal detectors.

School was closed on Tuesday. District officials said they planned to offer counseling for students.